Chronic pulmonary infection and associated airway obstruction are major factors in the pathophysiology of cystic fibrosis (CF). Previous work in this laboratory demonstrated the presence of an activity in CF serum which specifically inhibits phagocytosis of Pseudomonas by normal human alveolar macrophages (AM). This activity appears to correlate with Pseudomonas infection. Using techniques we developed for the separation of CF AMs from the debris in CF lung lavage fluid, AMs from CF patients have been shown to be capable of phagocytizing Pseudomonas in the presence of normal serum but are inhibited in CF serum. Ultrastructure studies support this observation since there is no morphological suggestion of in vivo bacterial phagocytosis by CF macrophages. This project is designed to extend these findings by correlating in vitro observations with the assessment of the in vivo status as a function of the stage of the disease. To acheive this objective, lung cells from CF patients in various stages of the disease will be studied together with the milieu in which these cells exist. Lung cells are obtained from bronchopulmonary lavages, whereupon the types of cells present will be identified, quantified, and evaluated by electron microscopy. Immunoglobulin and complement levels of lung lavage fluid will be determined. The ability of alveolar macrophages and PMNS to phagocytize and kill bacteria will be studied and the effect of lung lavage fluid on these processes will be evaluated comparing lavage fluid from CF patients and control subjects. This analysis of the structure and function of CF lung cell population and milieu of these cells is necessary to better characterize the host response to chronic lung colonization by Pseudomonas. These findings will be correlated with colonization history and clinical status in order to determine if lung cell populations change with increasing age, length of Pseudomonas colonization, and overall clinical condition. Our access to lung lavage from healthy individuals and patients with CF insures that the primary disease state and infection related alterations can be assessed.